Damping device for the pickerstick of weaving looms



Ap 1957 Y J. PlCANOL 2,788,806

DAMPING DEVICE FOR THE PICKERSTICK OF WEAVING LOOMS Filed Nov. 2, 1953 2 Sheets-Sheet 1 Jalme lea/70f ITORIYIN United States Patent 6 DAMPING DEVICE FOR THE PICKERSTICK F WEAVING LOOMS Jaime Picanol, Zillebeke, near Ypres, Belgium Application November 2, 1953, Serial No. 389,824

4 Claims. (Ci. 139-468) The ever increasing picking speed of modern looms makes it harder and harder to solve the problem of braking the pickerstick and bringing it to a standstill at the end of its stroke. The velocity of the shuttle is being constantly increased, bringing greater and greater stresses to bear on the pickerstick, when the shuttle flies back in its box. Similarly, the efforts required from the pickerstick become larger and larger in order to provide a faster throw of the shuttle.

The conventional way of braking the picker-stick consists in mounting at the end of its stroke, elastic stops, generally of leather, which, by the very nature of the leather, butters the final impact without imposing a too violent elastic reaction on the picker-stick. Such means can however no longer cope with the present working speed of modern looms, either because the impact at the end of the stroke is too violent, or because the elastic reaction is too large.

It has then been attempted to reduce the drawbacks of such stops by making use of leather straps stretched between the branches of a rigid support in U-form, the free space left behind the aforesaid strap enabling same to unstretch and thus to damp the strain exerted on the picker-stick. Such stops have been found satisfactory within certain limits of speed, but nowadays they can no longer be properly relied upon due to the constantly increasing stresses to which the picker-stick is subjected.

The object of the invention concerns a damping mechanism which will provide weaving looms with new means capable not only of damping systematically the pickerstick at the end of its stroke, but also of excluding any systematic elastic reaction, so as to obtain a powerful braking action on the picker-stick in a rational and progressive way.

This device is based primarily on the fact that the pickerstick, at the end of its stroke, is being progressively stopped by thrusting itself against a resilient element which, whilst being carried along by the picker-stick, offers adequate resistance resulting from friction of aforesaid resilient element in motion, against a fixed element. Both resilient and fixed elements are so shaped, that the frictional resistance and the braking power become larger as the impact of the picker-stick increases. In this way, effects are obtained which are the very opposite of those which are produced by the traditional type of stop.

Tests carried-out with this new mechanism have proved that the picker-stick undergoes practically no reaction effect, i. e. that the device does not restore any energy capable of making the picker-stick rebound. Hence we see, that this device is not only particularly efiicient as a brake and as a means of bringing the picker-stick to a standstill at the end of its stroke, but that it considerably reduces the strain on the picker-stick and minimizes wear and tear. In a similar way, the elements of the brakes are being strained in such a way, that fatigue and wear are considerably reduced, The same mechanism can be applied as a brake to the picker-stick both at the end of ice the outward throw and at the end of the backward stroke when the shuttle returns to its box.

By way of example, one mode of construction is described hereafter with reference to the appended drawings in which:

Figure 1 is a partial perspective view of a loom showing the location of the braking or damping mechanism;

Figure 2 is a very much simplified schematic representation of the damping mechanism for arresting the picker-stick at the end of the picker throw;

Figure 3 is a very much simplified schematic repre-F sentation of the damping mechanism for arresting the picker-stick at the end of the stroke caused by the thrust of the returning shuttle;

Figure 4 is a bottom plan view of the device;

Figure 5 is a section along line V-V of Figure 4; and

Figures 6 and 7 are sections along line VIVI of Figure 5 showing two diiferent positions of one of the strap engaging arms.

In these figures, the damping mechanism consists of two devices. One of these devices is intended to damp the stressm onor the movements of the picker-stick at the end of a picker-throw. This device consists of a comparatively resilient element, such as the strap 1 of an appropriate material, such as leather, textile, embedded textile, combination of leather and textile, plastic material or others. This strap is arranged as a loop supported by two platforms 2 located on either side of the passage provided for the picker-stick and secured to the lay of the loom (Figure 1). These platforms 2 are each provided with a guide 3 which determines the position of the strap before it comes into contact with the pickerstick which must be stopped. That part of the strap which corresponds to the actual loop, i. e. the part which surrounds said guide 3, is reinforced by a lining 5 fixed by means of rivets 6. The guide 3 as well as the strap 1, are shaped in such a way that the bottom of the loop forms a curve 8 whose diameter corresponds to the thickness of the picker-stick. Both ends 9 and 10 of the strap 1, are attached by bolts 11 and 12 to fixed drums 13 and 14 fastened at the ends of fixed arms 15 and 16 by spindlebolts 17 and 18. Each of the drums 13 and 14 has two elongated openings, of which one opening 19 is made near the lower edge of the drum whilst the other opening 20 lies near the upper edge. The spindle 17, say, carries, mounted freely end-to-end, two hubs 21 and 22, and between them is tightly wound a spiral spring 23 (Figure 5 Hub 21, comprises an arm 24 which passes through the oblong opening 19 and is formed into a hook 25 at the outer end; similarly, the second hub has an arm 26 which passes through the oblong opening 20 and terminates by a hook 27. Both drums 13 and 14 are identical but their springs are wound in opposite direction. The strap 1 is so conditioned that one of its ends Wound around drum 13 and fixed to it by bolt 11, has a lateral opening 28 through which passes the corresponding arm 24, whereby the part of the strap comprised between aforesaid arm 24 and the attaching bolt 11 is unstretched, i. e. has a greater length than the corresponding arc of drum 13. Similarly, the second free end of strap 1, affords a passage through the lower arm of drum 14 and is conditioned exactly like the first end. The result of this is, that when the picker-stick 4 thrusts itself against the bottom of the loop 8, both parts 29-30 of strap 1, maintained in close contact with the fixed drums 1314 tied to the lay by the action of the springs 23, engender the necessary friction to act as a brake to the picker-stick at the end of a picking stroke.

If We now consider the picker-stick in itself, at the end of a picking stroke, it will be noticed that it exerts a continuous effort against the strap at the bottom of the loop 8. As the strap is duly centred on the picker-stick 3 V 4 by aforesaid loop 8, the frictional efforts on each of the drums 13-14 will be equal. Consequently, the friction of strap 1 on these drums will be maintained until the picker-stick has come to a standstill. As aforesaid strap and, for a given length of the strap 1, the parts 293l o-f' aforesaid strap, in contact with the drums 13-44, will become correspondingly larger or smaller, and so will the frictional efforts.

The adjustments will thus have to be made in such a way that the friction is exactly right to damp the pickerstick 4 after-a picking-stroke.

The same applies when the device is adapted as a brake to the backstroke of the picker-stick, i. e. for damping the blow and stopping the motion'resulting from the return of the shuttle in its box: in this case, the device comprises a strap. 3,1 reinforced by a lining 50 formed as a loop 32, one end of which is attached by a bolt 33 to the drum 13, and whose other end is fixed by bolt 34 to drum 14. Just as was the case for the first strap 1, this strap 31 is traversed by the arms 26' and the part lying between these arms 25' and the corresponding fixing bolts 33-34 is kept unstretched, i. e. is made longer than the corresponding arc of the drums.

As the blow to be damped here is a good deal lighter than the one resulting rom the picking-stroke, aforesaid loop 32 is tied to a centering strap 36 by rivets 35. This centering strap 36 terminates at each end by a closed loop 37 maintained by rivets 38. Gn the other hand, the fixed arms -16 are assembled in form of a horse-shoe whose bottom 39 carries a slide 45!; a yoke 41 is fitted to it, and the two branches =%243 of this yoke carry fingers or studs M- iiwhich enter the end loops 37 of the centering strap 36 to which loop 32 is riveted. The distance of the studs, center-to-center is smaller, by a definite quantity, than the distance center-to-center of the loops 37, sov that the strap 36 allows a displacement of the loop 32 which is considerably in excess of the displacement which is needed for damping the picker-stick 4 whose movement is anyway limited by a fixed stop #6 held by rivet 49 to bracket 39. The rest position of loop 32 is obtained by springs 23 which exert a comparatively weak traction on strap 31 and maintain strap 36 under tension before the picker-stick 4 comes in.

Apart from that, the position of the loop 32, and thus the damping depth of the sword is adjustable; to this 'efi'ect, part 41 which carries the studs 4445, can be moved in the slide 41 and is fixed after adjustment, by bolt 47 and nut 48.

The distance to be provided between the loop 32 and the fixed stop 46, or which is the same, the damping V depth of the picker-stick, will thus be the one which is required for progressive damping of the sword. Figure 4 shows clearly that the greater this distance has been taken, the larger will bethe surfaces 5152 of strap 31 which come into contact with the drums, and the larger the friction will be.

This then affords two possibilities: either a greater damping depth of the sword, coupled with more powerful braking, or conversely, a lesser damping depth with comparatively weak braking.

When picker-stick 4 reaches the end of its backward stroke, it pushes against strap 31 at the bottom of loop 32, thus giving rise to frictions between aforesaid strap and the drums 1314 in accordance with the process described for strap 1.

Under these conditions, the picker-stick has a braking action, applied to it at the end of either stroke by one and the same process, with the result that the sword is brought 4 to a standstill progressively but without any elastic reaction, because the springs 23 are not sufficiently strong to give rise to rebound; in fact, their function is limited to return the straps 1 and 31 in their initial position, and

to apply the parts 293051 and 52 permanently.

against the drums.

This lateral braking effect on the picker-stick can evidently be obtained by other than the above named means; so for instance, the loop ends of the strap could be elas- 'cally anchored or acted upon in any other way than that which hasv been described and illustrated.

it is also evident, that the object of the invention could,

' a lay, of a damping device for the throw of the; pickerstick comprising a strap bent into a V in it middle portion, means to support said V-shaped portion ofsaid strap, a pair of spaced stationary drums. to which the.

outer ends of said strap are rigidly secured, means to;

vary the distance between said drums and. said support means, each of said. drums having an elongated aperture in its side wall, a spring actuated arm pivoted within each of said drums, projecting through said aperture and engageable' with said strap at a point adjacent the peripheryof said drum so as to maintain a portion of the part of said strap extending between said arm and said V-shaped middle-portion in frictional contact with said drum, the portion of said strap which extends between said arm and its outer end secured to said drum loosely extending around said drum whereby the impact of said picker-stick on said V-shaped portion of said strap will be resisted by frictional sliding of said strap on each of said drums and-said picker-stick will be positively stopped when said strap becomes completely stretched. V

2. In a loom a claimed in claim 1, including a yoke secured to said lay and at the free ends of which said drum are fixedly mounted, a coaxial shaft mounted within each of said drums, a spring urged hub rotatably mounted on each of said shafts and from which said arms depend;

V 3. In a loom as claimed in claim 2, further including a second hub mounted on said shaft in each of saiddrums, a second arm depending from said second hub and projecting through an elongated opening made in the side wall of said drum, a second strap bent into a V in its middle portion, facing the V-shaped middle portion of the first named strap and having its outer ends secured to said drum and engageable by said second arm at points spaced from said free ends adjacent the periphery of said drums whereby said second strap will retard and arrest said picker-stickat the end of the stroke of the latter opposite the end of said stroke at which said pickerstick is arrested by said first named strap;

4. In a loom as claimed in claim 3, further including a centering strap secured at its middle portion to the V-shaped portion of said second strap, arms on which the outer ends of said centering strap are mounted, said arms being adjustably secured to said yoke so as to vary the distance of the middle portion of said centering strap from said drums.

References Cited in the file of this patent UNITED STATES PATENTS 676,658 Mills June 18, 19.01 1,587,149 Cotchett June 1, 19.26 1,863,127 Sakamoto June, 14, 1932 FOREIGN PATENTS 7 313,922 Great Britain May 29, 1930 610,872 Great Britain Oct; 21, 19,48 

